Introduction
Celiac Disease (CD) is a prevalent autoimmune disorder, instigated by gluten, affecting approximately 1% of the UK’s population. This disease presents with a range of symptoms, including diarrhoea, bloating, and unexplained weight loss. However, many sufferers remain undiagnosed due to the non-specific nature of these symptoms. The only available treatment for CD is a strict, lifelong gluten-free diet. This can significantly impact the patient’s quality of life. Therefore, the accuracy and cost-effectiveness of a CD diagnosis is crucial.
The Consequences of Undiagnosed CD
Failure to promptly diagnose and treat CD can lead to severe complications. Damage to the small intestine’s surface and difficulties absorbing nutrients can result in malnutrition and anaemia. If left untreated, CD may also increase the risk of serious complications such as lymphoma and osteoporosis.
The Diagnostic Pathway for Celiac Disease Screening
The diagnostic pathway for CD involves identifying those at risk, serological testing to identify potential CD, and a biopsy of the small intestine to confirm the diagnosis. There are several serological tests available for CD in the UK. These include testing for immunoglobulin A (IgA) and IgA anti-tissue transglutaminase (tTG). Some guidelines also recommend IgA endomysial antibody (EMA) testing after tTG testing.
The Role of Genetic Testing in CD Diagnosis
Genetic testing, due to CD’s strong genetic basis, has the potential to be used as a “rule out” test. Absence of either of the human leukocyte antigen (HLA) DQ2/DQ8 genetic markers suggests it is highly unlikely that the person tested has CD. However, UK guidelines do not currently recommend HLA DQ2/DQ8 testing as an initial screening test for CD diagnosis.
The Cost-Effectiveness of Celiac Disease Screening
A recent study from the UK aimed to estimate the most cost-effective pre-test probability which all patients should be screened for in the country. They also aimed to address which serological tests should be used. Furthermore, whether genetic testing should be included, and whether a confirmatory biopsy would be needed. Lastly, they aimed to identify uncertainties that have the greatest impact on cost-effectiveness results, thus identifying priorities for future research.
Comparative Analysis with Other Studies
Their findings, which advocate for the cost-effectiveness of IgA EMA, IgA tTG, and HLA testing, either alone or in combination, for at-risk patients align with previous models. For instance, a study by Ladabaum 2004 found tTG to be cost-effective at $50,000 if the pre-test probability was 2% and at $100,000 if the pre-test probability was 1.1%. Similarly, Herchcovici 2010 used a Markov model to conclude that mass screening via serological test followed by biopsy was cost-effective compared to no screening.
International Perspectives on CD Screening
In an international context, Mohseninejad 2013 found that screening patients with irritable bowel syndrome (IBS) symptoms for CD was cost-effective in the Dutch setting. Meanwhile, Norström et al, 2021 discovered population screening at age 12 using IgA EMA to be cost-effective at a Є50,000 per quality-adjusted life-year (QALY) willingness-to-pay (WTP) threshold, compared with no screening in the Swedish setting. The model by Keeney et al, largely followed the evidence-based structure used in the National Institute of Clinical Excellence (NICE) guideline model, with deviations based on clinical opinion and analysis of the Clinical Practice Research Datalink (CPRD) data sets.
Conclusion
In conclusion, the economic burden of CD and its impact on the quality of life of patients necessitates a cost-effective diagnostic strategy. Current evidence suggests that serological tests, such as IgA EMA and IgA tTG, in combination with HLA testing, provide a cost-effective approach for the screening of at-risk patients. It’s worth noting that the pre-test probability of CD significantly impacts these tests’ cost-effectiveness. We need more research to clear uncertainties in the diagnostic pathway. It’s also essential to enhance screening strategies for CD.
